The original Rocksmith had a lot going for it, but was made frustrating by a number of bad design decisions and technical issues. This new version, if it lives up to the description, looks nearly perfect. Just the fact that you can jump directly into the riff repeater from the middle of a song to work on just that section, then immediately jump back to the song once you got it, is exactly how it should have always worked.
I use backing tracks all the time to practice improvisation. Using Rocksmith’s new “Sessions” mode to generate backing tracks in different styles, tempos and keys should be extremely useful.